Given concerns with the low levels of explanation in science education classrooms, it has been suggested that text may supply a higher percentage of explanatory discourse than do classroom teachers. However, given that textbooks have been shown to differ little from teacher discourse in percentages of explanation, the present study sought to examine explanatory aspects of highly recommended trade books teachers might use in their science instruction. To that end, we examined a total of 43 trade books, 24 life science and 19 physical science, 7182 clauses in all, for the presence of explanation. We found significantly higher percentages (32.87) of explanatory clauses in physical science trade books than in life science (23.34) trade books. This trend was particularly pronounced in the physical science trade books targeted for the primary-grade audience. Our results suggest that trade books may represent an option for infusing more focus on explanation in the science classroom. However, we also caution that teacher background may limit the effectiveness of this larger presence of explanation. (Contains 5 tables.)